We will continue our investigation of enzyme systems whose formation is regulated by glutamine synthetase, and of the role of glutamine synthetase in the regulation of its own synthesis. We are using Klebsiella aerogenes as the test organism, and we are applying genetic and biochemical methods in these investigations. BIBLIOGRAPHIC REFERENCES: Struhl, K., and Magasanik, B. Ammonia-sensitive mutants of Klebsiella aerogenes. J. Bacteriol. 126:739-742. (1976). Resnick, A.D., and Magasanik, B. L-Asparaginase of Klebsiella aerogenes. J. Biol. Chem. 251:2722-2728 (1976).